Dirty Air Raises Death Risk for U.S. Seniors Even at Low Levels

Air pollution may shorten the lives of American seniors, even in areas where levels fall below national safety standards, new research indicates.

Although it's possible that factors other than air pollution are responsible for the increase in premature deaths among older adults, study co-author Francesca Dominici said the findings are "bulletproof evidence of increased risk of deaths due to polluted air in the United States.”

"Make no mistake. We need to strengthen, not weaken, [U.S. Environmental Protection Agency] air pollution standards," said Dominici, a professor of biostatistics at Harvard T.H. Chan School of Public Health in Boston. "We need to increase, not reduce, the EPA research funding."

The investigators launched their research to determine whether pollution levels considered to be acceptable might still be hazardous to human health.

"There is extensive evidence on the harmful effects of air pollution on human health," Dominici said. "But what we don't know is whether these harmful effects persist at air pollution levels below the National Ambient Air Quality Standards — safety standards set by the EPA."

It's also not clear which groups of people may be most vulnerable, she added.

Dominici's team analyzed health records of 61 million seniors who were covered by Medicare in the lower 48 states from 2000 to 2012. The researchers looked for links between death rates and local air pollution levels, as determined by zip code.

The researchers looked at levels of fine particulate matter, also known as PM2.5 (particulate matter 2.5 micrometers or less in diameter). They linked increases in PM2.5 pollution of 10 micrograms per cubic meter to a 7.3 percent increase in death rates. But the study did not prove that air pollution caused death risk to rise.

Still, "we found increased risk of deaths for small increases in air pollution levels, even in areas that have low pollution levels," Dominici said.

The investigators also found evidence that men, black people and the poor faced an even higher risk of early death. The effect on blacks appeared to be three times that of the entire population studied, they said.

These groups may be more susceptible to the effect of population due to "living conditions, unhealthy behavior, lower access to health care and maybe receiving poorer health care," Dominici noted. Health conditions like chronic diseases could also play a role, she said.

"If we would reduce the annual average of PM2.5 by just 1 microgram per cubic meter nationwide, we should save 12,000 lives every year," Dominici said. She added that reducing that level by five micrograms could save almost 64,000 lives every year.

The study was published June 29 in the New England Journal of Medicine. Dr. Jeffrey Drazen, editor-in-chief of the journal, co-wrote an editorial that said the study adds "to the large body of evidence indicating the risks of air pollution, even at current standards" and shows that "we must redouble our commitment to clean air." Drazen said the work suggests that more stringent rules about air pollution will save lives.

But is he only preaching to the choir?

"We cannot predict the political impact of this work," Drazen said. "We can only bring these facts to the attention of the American people."